CALCULUS
posted by bri .
what is the area in square units of the region under the curve of the function f(x)=x+3, on the interval from x=1 to x=3?
10
12
14
16
18 ?

even without calculus, since this is just a trapezoid with bases 4 and 6, height 2.
5*2 = 10
now, using calculus, integrate under the curve, from 1 to 3
integral[1,3] x+3 dx
= x^2/2 + 3x [1,3]
= (9/2 + 9)  (1/2 + 3) = 10